Changes in cerebral activity after decreased upper-limb hypertonus: An EMG-fMRI study

Paolo Manganotti, Michele Acler, Emanuela Formaggio, Mirko Avesani, Franco Milanese, Andrea Baraldo, Silvia Francesca Storti, Anna Gasparini, Roberto Cerini, Roberto Pozzi Mucelli, Antonio Fiaschi

Research output: Contribution to journalArticlepeer-review


Objective: Whereas several studies have used functional magnetic resonance imaging (fMRI) to investigate motor recovery, whether therapy to decrease post-stroke hypertonus alters central motor patterns remains unclear. In this study, we used continuous electromyography (EMG)-fMRI to investigate possible changes in movement-related brain activation in patients receiving Botulinum toxin (BoNT-A) for hand-muscle hypertonus after chronic stroke. Methods: We studied eight stroke patients all of whom had hemiparesis and associated upper-limb hypertonus. All patients underwent an fMRI-EMG recording and clinical-neurological assessment before BoNT-A and 5 weeks thereafter. The handgrip motor task during imaging was fixed across both patients and controls. The movements were metronome paced, movement amplitude and force were controlled with a plastic orthosis, dynamometer and EMG recording. An age-matched control group was recruited from among healthy volunteers underwent the same fMRI-EMG recording. Results: Before BoNT-A, while patients moved the paretic hand, fMRI detected wide bilateral activation in the sensorymotor areas (SM1), in the supplementary motor area (SMA) and cerebellum. After BoNT-A blood oxygenation level-dependent (BOLD) activation decreased in ipsilateral and contralateral motor areas and became more lateralized. BOLD activation decreased also in ipsilateral cerebellar regions and in the SMA. Conclusion: Changes in peripheral upper-limb hypertonus after BoNT-A were associated to an improvement in active movements and more lateralized and focalized activation of motor areas. The clinical and EMG-fMRI coregistration technique we used to study hand-muscle hypertonus in patients receiving BoNT-A after chronic stroke should be useful in future studies seeking improved strategies for post-stroke neurorehabilitation.

Original languageEnglish
Pages (from-to)646-652
Number of pages7
JournalMagnetic Resonance Imaging
Issue number5
Publication statusPublished - Jun 2010


  • Botulinum toxin
  • EMG
  • FMRI
  • Spasticity
  • Stroke

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging
  • Biomedical Engineering
  • Medicine(all)


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